Cannula provided with a sealing element for use in a medical procedure

ABSTRACT

A cannula assembly includes an outer tube having a proximal portion, a distal portion, and a lumen. The outer tube defines a longitudinal axis. An inner tube is disposed within the lumen of the outer tube. A cap is connected to the proximal portion of the outer tube. The cap has a recessed portion that defines an interior wall. The recessed portion extends proximally from the lumen of the outer tube. A stopper is configured to be slidably received in the recessed portion of the cap. The stopper has a through hole located on the longitudinal axis and configured to receive the inner tube. An inner seal is interposed between the stopper and the inner tube. An outer seal is interposed between the stopper and the interior wall of the cap.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 10/549,820,filed Sep. 20, 2005, as a national application under 35 U.S.C. § 371 ofInternational Application Serial No. PCT/EP04/03327 filed Mar. 29, 2004,the entireties of which are incorporated herein by reference.

This application is related to U.S. patent application Ser. No.11/680,917, filed Mar. 1, 2007, which is a continuation of U.S. patentapplication Ser. No. 10/549,820, filed Sep. 20, 2005.

MICROFICHE APPENDIX

None

GOVERNMENT RIGHTS IN PATENT

None

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to medical devices, and, moreparticularly, to a cannula provided with a sealing element for use in amedical procedure.

2. Description of the Related Art

Known from DE GMS 202 09 525.8 is a coaxial cannula that can be insertedinto tissue and in which a biopsy needle unit can be employed. A seal isprovided between the interior wall of the coaxial cannula and theexterior wall of the biopsy needle unit in order to, first, preventfluid from escaping and, second, to make it possible to create a vacuumin the tissue to be biopsied. DE GMS 202 09 525.8 states that thesealing function of the seal must be created such that it prevents airfrom entering or escaping and also prevents fluid from escaping.

Such a seal has led to problems in practice. When inserting the biopsyneedle unit into the coaxial cannula and during subsequent positioningof the needle unit, the air that has penetrated into the coaxial cannulaas a result of the insertion process is sealed in and air bubbles formthat cause problems with the ultrasound or MR images made while theneedle is being positioned so that precise positioning is not possibledue to the air occlusions.

SUMMARY OF THE INVENTION

The invention relates to a coaxial cannula that can be employed intissue, in which for removing tissue are a biopsy needle unit withspecimen removal space and a longitudinally movable specimen separatingdevice that coaxially encloses the biopsy needle on the exterior wall,and whereby the coaxial cannula has on its proximal end a sealingelement that encloses the space between the interior wall of the coaxialcannula and the exterior wall of the specimen separating device.

The sealing element releases the air outlet when the needle unit isinserted and prevents air from entering after the needle unit has beenpositioned and a vacuum has been created in the biopsy needle interiorspace.

Due to such an embodiment of the seal, on the one hand air that has beencompressed by inserting the needle unit can escape so that no occludedair bubbles are formed and ultrasound or MR images are not affected ordisrupted.

The invention in one form thereof is directed to a cannula arrangement.The cannula arrangement includes an outer tube and an inner tube. Theouter tube has a proximal end and a distal end. The inner tube isdisposed within the outer tube to define a space between an innersurface of the outer tube and an outer surface of the inner tube. Asealing element is mounted at the proximal end of the outer tube. Thesealing element has a projecting portion that projects proximally fromthe proximal end of the outer tube. The projecting portion has aprojecting end that has an interior edge to contact the outer surface ofthe inner tube.

The invention in another form thereof is directed to a cannula. Thecannula includes a tube having a proximal end and a distal end. Asealing element is mounted at the proximal end of the tube. The sealingelement has a projecting portion that projects proximally from theproximal end of the tube. The projecting portion has a projecting endthat is curved inwardly and has an interior sealing edge.

The invention in another form thereof is directed to a method of ventinga cannula. The method includes forming a seal with a sealing elementprojecting from a proximal end of an outer tube so that an edge of thesealing element is flexibly pressing against an outer surface of aninner tube slidably disposed within the outer tube to form the seal, theseal resisting a distal movement of a fluid into a space defined by aninner surface of the outer tube and the outer surface of the inner tube;and moving the edge at least in part away from the outer surface of theinner tube to break the seal and allow the passage of aproximally-moving fluid from the space.

The invention in another form thereof is directed to a medical device.The medical device includes a coaxial cannula for use in tissue, thecoaxial cannula having an interior wall. A biopsy needle unit isconfigured for insertion into the coaxial cannula. The biopsy needleunit has an exterior surface, and when inserted into the coaxial cannulaan intermediate space is formed between the interior wall of the coaxialcannula and the exterior surface of the biopsy needle unit. An elasticsealing element defines a sealing lip, the sealing lip having aninterior edge. The elastic sealing element is mounted to the coaxialcannula, wherein the interior edge of the sealing lip is located to sealagainst the exterior surface of the biopsy needle unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings.

Exemplary embodiments are described in detail as follows:

FIG. 1 is an exploded depiction of a coaxial cannula with mandrel;

FIG. 2 is a section through the cap of a coaxial cannula (variant A,enlarged);

FIG. 3 is a section through the cap of a coaxial cannula acting togetherwith a guide roller on the biopsy device (variant B, enlarged); and

FIG. 4 is a section through the coaxial cannula cap using anintermediate piece and a guide roller on the vacuum biopsy device.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate embodiments of the invention and such exemplifications arenot to be construed as limiting the scope of the invention in anymanner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to FIGS. 1 and 2,there is shown a coaxial cannula arrangement in accordance with anembodiment of the invention.

FIG. 1 illustrates a coaxial cannula with mandrel in an explodeddrawing. A cap 2 is connected to the coaxial cannula tube 1 (“tube” forshort). For attaching the tube 1, the latter projects into an interiorbore 4 of the cap 2 at its proximal end 5 into the cap (FIG. 2). Forexample, a clamping seat holds the proximal tube end 5 in the cap. Asealing element 3, e.g., a hose piece, is placed over the proximal tubeend 5. For inserting the coaxial cannula into the tissue, a mandrel 6(press-in mandrel) is inserted into the coaxial cannula and the mandrelcap 7 is screwed to the cap 2. When assembled, the mandrel tip 8projects beyond the distal end of the tube.

The coaxial cannula is inserted together with the mandrel into thetissue, e.g., by pressing it in, specifically such that, for example bymeans of ultrasound equipment, the mandrel tip of the mandrel is guidedto or placed in the vicinity of the tissue to be examined.

Once the coaxial cannula has been inserted by means of the mandrel, themandrel is withdrawn and removed; e.g., by unscrewing the connection tothe proximal end. In order to prevent rotation or a change in thepositioned coaxial cannula, surfaces are provided on the coaxial cannulain which a fork or clamp that is connected via additional elementsengages, e.g., to the operating or examining table, so that the coaxialcannula is held in the selected position.

After the coaxial cannula has been inserted and positioned, and afterthe mandrel has been removed, the needle unit 9 of a vacuum biopsydevice with or without an externally arranged cutting sleeve 21(specimen separating device) is inserted into the tube 1 of the coaxialcannula (FIG. 2). The needle unit 9 comprises, for example, a hollowneedle with a cutting sleeve 21 that encloses it coaxially and has acutting edge on the distal side. However, the needle apparatus can alsobe an exterior hollow needle in the hollow space of which the cuttingdevice is coaxially arranged. Instead of the mandrel cap, now the endface, for example of a sterile guide roller 13 of the vacuum biopsyequipment, sits against the proximal end face 10 of the cap 2 (see alsoFIGS. 3 and 4). After insertion, the end face of the guide roller 13 ofthe vacuum biopsy device sits on the end face 10 of the cap. When theneedle unit is inserted, the air that penetrated after the removal ofthe mandrel can at first escape until the sealing lip 11 is drawn to theexterior surface of the needle unit by a vacuum created in the hollowneedle; i.e., the part of the sealing element that projects beyond thecannula tube on the proximal side is designed so that when the needleunit is inserted a slight gap remains open between the sealing lip andthe exterior surface of the needle unit; this occurs, for instance, byhaving only one edge 12 of the sealing lip touch the exterior surface.When a vacuum is created in the hollow space of the biopsy needle, theunderpressure increases the pressure force so that the sealing lip 11,that is, the free hose end, is pressed against the exterior surface ofthe needle unit, thus preventing the entry of more air.

The use of an appropriately dimensioned hose that is placed over theproximal end of the coaxial hose is a simple, inexpensive, yet effectiveembodiment of the sealing element. Care should be taken that theflexibility of the hose is such that during insertion the suction effectat slight underpressure securely closes the gap present between theinterior wall of the coaxial cannula and the exterior wall of the needleunit. Specifically, this is attained by using suction to draw theproximal end, e.g., the interior edge, of the hose against the exteriorside of the needle unit. For this reason the proximal end of the hose ispreferably slightly curved toward the needle unit so that when thevacuum is created the projecting part of the hose piece is drawn inwardand pressed against the exterior surface of the needle unit. Removingthe vacuum, the underpressure, in the needle hollow space cancels thesealing effect and the gap reopens due to the elasticity of the hose.

However, the sealing element can also be part of the vacuum biopsydevice (e.g., in accordance with DE GMS 202 04 363), in particular whenthe biopsy device is equipped with a guide roller. In this case astopper on the distal side at the guide roller is provided that acts asa sealer to engage a corresponding coupling bore in the cap of thecoaxial cannula. If the sealing elements do not enter into thecounterpart until just prior to the device being placed onto thecounterpart into the countercoupling parts, the air can exit first.Thus, the effect does not occur until just before the closing so that noair bubbles or air occlusions disrupt the ultrasound or MR images.

If an intermediate piece is used between the guide roller and theproximal surface of the coaxial cap to reduce the penetration depth ofthe biopsy needle unit, the intermediate piece has one coupling piece onthe distal side and one on the proximal side so that the stopper of theguide roller can, first, act as a seal, and second, the intermediatepiece can act as a seal in the coupling cap. The intermediate spacebetween the needle unit and the coaxial cannula is not closed until justprior to the final positioning of the needle unit so that the air canescape and is not compressed.

In the examples illustrated in FIGS. 3 and 4, alternatives for theembodiment of the sealing function, the guide roller 13 does not sitflush with the end face 10 of the cap, and there is also no sealingelement arranged on the proximal end of the tube 1, but instead theguide roller of the biopsy device has a stopper 14 that is inserted intoa coupling counterpart 15 provided in the cap 2. The stopper seals theexterior surface of the needle unit against the guide roller via theseal 16. The cap is sealed against the stopper of the guide roller bymeans of the seal 17. Both seals are designed, for example, as O-rings.Because the stopper is kept very short in its longitudinal extension(e.g. stopper length is 5 mm), the sealing effect does not occur untiljust prior to placing the guide roller on the cap. In other words, thesealing effect does not occur until just before the needle tip ispositioned. Air that is present in the coaxial cannula can escape untilthe sealing effect occurs.

FIG. 4 illustrates the same arrangement as FIG. 3, but in this case inorder to reduce the penetration depth of the needle unit an intermediatepiece 18 is inserted between cap 2 and guide roller 13. The intermediatepiece has on its distal side a stopper 14 that is inserted into thecoupling counterpiece. The seal between the cap-side couplingcounterpiece of the coaxial cannula and the stopper 14 occurs via theseal 19. The stopper 14 of the guide roller is the same as that alreadydescribed (FIG. 3) and is inserted into a coupling counterpiece 20 ofthe intermediate piece 18, which is arranged on the proximal side. Thesealing arrangement is the same as that described for FIG. 3. In thiscase, as well, the sealing effect does not occur until just before thetip of the needle unit is brought into its final position. This meansthat the air that has penetrated can escape from the hollow cannuladuring the insertion process. The intent of both solutions is that theair that has penetrated into the coaxial cannula when the mandrel isexchanged for the needle unit can escape to the greatest extent possiblewhen the needle unit is inserted so that no disruptions occur during theuse of ultrasound or MR.

While this invention has been described with respect to at least oneembodiment, the present invention can be further modified within thespirit and scope of this disclosure. This application is thereforeintended to cover any variations, uses, or adaptations of the inventionusing its general principles. Further, this application is intended tocover such departures from the present disclosure as come within knownor customary practice in the art to which this invention pertains andwhich fall within the limits of the appended claims.

1-17. (canceled)
 18. A cannula assembly, comprising: an outer tubehaving a proximal portion, a distal portion, and a lumen, the outer tubedefining a longitudinal axis; an inner tube disposed within the lumen ofthe outer tube; a cap connected to the proximal portion of the outertube, the cap having a recessed portion that defines an interior wall,the recessed portion extending proximally from the lumen of the outertube; a stopper configured to be slidably received in the recessedportion of the cap, the stopper having a through hole located on thelongitudinal axis and configured to receive the inner tube; an innerseal interposed between the stopper and the inner tube; and an outerseal interposed between the stopper and the interior wall of the cap.19. The cannula assembly of claim 18, wherein the inner seal is a firstO-ring and the outer seal is a second O-ring.
 20. The cannula assemblyof claim 19, wherein the stopper includes an inner groove and an outergroove, the first O-ring being positioned in the inner groove and thesecond O-ring being positioned in the outer groove.
 21. A cannulaassembly, comprising: an outer tube having a proximal portion, a distalportion, and a lumen; a cap having a coupling counterpart providedtherein, the cap being connected to the outer tube; an inner tubedisposed within the lumen of the outer tube; a guide roller having astopper that is inserted into the coupling counterpart provided in thecap; an inner seal interposed between the inner tube and the stopper ofthe guide roller; and an outer seal interposed between the couplingcounterpart of the cap and the stopper of the guide roller.
 22. Thecannula assembly of claim 21, wherein the coupling counterpart of thecap is a recessed portion that defines an interior wall within the cap.23. The cannula assembly of claim 21, wherein the cap has an end face,and the guide roller is configured to engage the end face of the cap.24. The cannula assembly of claim 21, wherein the inner seal is a firstO-ring and the outer seal is a second O-ring.
 25. The cannula assemblyof claim 24, wherein the stopper includes an inner groove and an outergroove, the first O-ring being positioned in the inner groove and thesecond O-ring being positioned in the outer groove.
 26. A cannulaassembly, comprising: an outer tube having a proximal portion, a distalportion, and a lumen; a cap having a coupling counterpart providedtherein, the cap being connected to the outer tube; an inner tubeslidably disposed within the lumen of the outer tube; and a guide rollerhaving a stopper configured for insertion into the coupling counterpartprovided in the cap, the stopper having an inner groove and an outergroove, and having an inner seal positioned in the inner groove and anouter seal positioned in the outer groove; and wherein a sealing effectoccurs when both the inner seal is interposed between the inner tube andthe stopper of the guide roller and the outer seal is interposed betweenthe coupling counterpart of the cap and the stopper of the guide roller,and wherein the stopper has a longitudinal extension that includes theinner groove and the outer groove, the longitudinal extension configuredsuch that as the stopper of the guide roller is inserted into thecoupling counterpart of the cap, the inner seal is interposed betweenthe inner tube and the stopper of the guide roller prior to the outerseal being interposed between the coupling counterpart of the cap andthe stopper of the guide roller so that air that is present in the outertube can escape until the sealing effect occurs.
 27. The cannulaassembly of claim 26, wherein the longitudinal extension of the stopperof the guide roller has a length of five millimeters.
 28. The cannulaassembly of claim 26, wherein the inner seal is a first O-ring and theouter seal is a second O-ring.